CN115254950A - Method for improving performance uniformity of screw-thread steel poker produced by hot-feeding and direct-rolling - Google Patents

Abstract

The invention belongs to the technical field of iron and steel production, and relates to a method for improving the performance uniformity of threaded steel bars produced by hot-feed direct rolling, comprising the following steps: 1) batching; 2) converter smelting, and 3) continuous casting: adopting hot-feed direct rolling The production process is organized by using the temperature of the continuous casting billet itself for rolling. The continuous casting billet needs to be insulated before cutting, and the speed of the insulation roller table is controlled at 1.5m/s. 4) Transfer to the rolling mill: After cutting, it is quickly sent to the rolling mill for rolling through the high-speed roller table; 5) Rolling: the rolling temperature is 955~985℃, and the temperature of the finishing rolling I: 850~870 ℃, the temperature of the finishing rolling II is 850-870 ℃, and the temperature of the upper cooling bed is 860-880 ℃; 6) Inspection, packaging and storage. Aiming at the problem of large fluctuations in the yield strength of the HRB400E head, middle and tail of the threaded steel, the invention reasonably optimizes the hot-feeding direct rolling process, so that the fluctuation of the yield strength of the HRB400E head, middle and tail can be realized within 15Mpa, and the uniform performance of the threaded steel bar is improved. sex.

Description

A Method for Improving the Uniformity of Performance of Rebar Cleaning Rod Produced by Hot Direct Rolling

technical field

The invention belongs to the technical field of iron and steel production, and relates to a method for improving the uniformity of performance of rebar strips produced by hot-sending direct rolling.

Background technique

The length of the existing hot direct rolling billet is generally controlled below 10m. For the continuous casting billet whose length reaches 12m, the section is generally 150mm×150mm～165mm×165mm, and the section size is 170mm×170mm. rare. The main reason is that the temperature difference between the head and tail of the continuous casting slab and the inside and outside is relatively large, and the rolling process requires the starting temperature to be ≥ 950°C. As a result, the performance of rebar cleaning rods fluctuates greatly, and the yield strength fluctuations of the head, middle and tail are greater than or equal to 30Mpa, which is not conducive to stable quality control.

Contents of the invention

In view of this, the object of the present invention is to solve the problem of large fluctuations in the yield strength of the rebar head, middle and tail, and to provide a method for improving the performance uniformity of the rebar pass rod produced by hot-sending direct rolling.

To achieve the above object, the present invention provides the following technical solutions:

A method for improving the performance uniformity of rebar cleaning rods produced by hot-sending direct rolling, comprising the steps of:

1) Ingredients;

2) Converter smelting: Calculate the required alloy according to the composition requirements of the ingredients, and smelt in the converter;

3) Continuous casting: Molten steel is poured into a qualified billet, and the production is organized by the hot-sending direct rolling process. The continuous casting billet is rolled at its own temperature. The continuous casting billet needs to be kept warm before cutting, and the speed of the heat preservation roller is controlled. At 1.5m/s, natural gas and oxygen heating devices are used to supplement the heat of the billet during the simultaneous cutting process;

4) Delivery to the rolling mill: After cutting, it is quickly sent to the rolling mill for rolling through the high-speed roller table. The high-speed roller table requires 4.0-5.5m/min to reduce the temperature drop at the head and tail of the billet and achieve the highest temperature at the head and tail of the billet. Temperature difference≤25℃;

5) Rolling: start rolling temperature 955-985°C, finishing rolling I temperature: 850-870°C, finishing rolling II temperature 850-870°C, upper cooling bed temperature 860-880°C;

6) Inspection, packaging and warehousing: Sampling and inspection of the rebar produced by the hot direct rolling process, and packaging and warehousing.

Furthermore, the rebar grade is HRB400E, and its composition is calculated by mass percentage: C: 0.22-0.25%, Si: 0.10-0.30%, Mn: 1.45-1.60%, P: ≤0.040%, S: ≤0.040%, and the rest For Fe and unavoidable impurities.

Further, in step 3), the section size of the billet is 170mm×170mm×12mm.

Further, in the heat supplement process in step 3), pressure regulating valve groups and control systems are installed on the respective main pipes to control the flow of gas and oxygen. The natural gas consumption requirement: 480Nm ³ /h, pressure > 0.2MPa, oxygen consumption requirement: 960Nm ³ /h, pressure ﹥0.2MPa, the flow rate of each flow can be adjusted according to the heating effect, the continuous casting billet is heated to 1000 ℃ ~ 1030 ℃, and the temperature difference between the head and tail of the billet is controlled below 25 ℃.

Further, in step 6), the yield strength test is carried out on the head, middle and tail of the rebar cleaning rod respectively. If the yield strength fluctuation is less than 15Mpa, it is qualified and packed into the warehouse.

The beneficial effect of the present invention is that: the present invention aims at the problem that the yield strength of the threaded steel head, middle and tail fluctuates greatly, rationally optimizes the hot direct rolling process, and can realize the fluctuation of the yield strength of the HRB400E head, middle and tail within 15Mpa, and realize the thread Uniformity of steel cleaning rod performance.

Other advantages, objects and features of the present invention will be set forth in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the investigation and research below, or can be obtained from It is taught in the practice of the present invention. The objects and other advantages of the invention may be realized and attained by the following specification.

Detailed ways

Embodiments of the present invention are described below through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation modes, and various modifications or changes can be made to the details in this specification based on different viewpoints and applications without departing from the spirit of the present invention.

A method for improving the performance uniformity of rebar cleaning rods produced by hot-sending direct rolling, comprising the steps of:

1) Ingredients: The grade of rebar is HRB400E, the nominal diameter is Φ16mm, and its composition is calculated by mass percentage: C: 0.23%, Si: 0.18%, Mn: 1.45%, P: 0.032%, S: 0.019%, and the rest is Fe and unavoidable impurities;

2) Converter smelting: Calculate the required alloy according to the composition requirements of the ingredients, and smelt in the converter;

3) Continuous casting: pouring molten steel into qualified billets, the section size of billets is 170mm×170mm×12mm; the production is organized by hot-sending direct rolling process, and rolling is carried out by using the temperature of the continuous casting billet itself, and the continuous casting billet Heat preservation is required before cutting, and the speed of the heat preservation roller is controlled at 1.5m/s. At the same time, natural gas and oxygen heating devices are used to supplement the heat of the billet during the cutting process; pressure regulating valve groups and control systems are installed on the respective main pipes. For gas and oxygen split flow control, natural gas consumption requirement: 480Nm ³ /h, pressure ﹥ 0.2MPa, oxygen consumption requirement: 960Nm ³ /h, pressure ﹥ 0.2MPa, the flow rate of each flow can be adjusted according to the heat supplement effect, and the continuous casting The billet is heated to 1000°C to 1030°C, and the temperature difference between the head and tail of the billet is controlled below 25°C.

4) Delivery to the rolling mill: After cutting, it is quickly sent to the rolling mill for rolling through the high-speed roller table. The high-speed roller table requires 4.8m/min to reduce the temperature drop at the billet head and tail, and reach the temperature difference between the billet head and tail ≤ 25°C;

5) Rolling: start rolling temperature head 962°C, tail 975°C, finishing rolling I temperature: 863°C, finishing rolling II temperature: 859°C; cooling stage: upper cooling bed temperature: 876°C;

6) Inspection, packaging and warehousing: The yield strength of the head, middle and tail of the rebar wire rod produced by the hot rolling process is tested respectively. The test results are: the yield strength of the head is 445MPa, the yield strength of the middle is 440MPa, and the yield strength of the tail is The strength is 450MPa, with a maximum difference of 10MPa; the tensile strength of the head is 635MPa, the central part is 635MPa, and the tail is 630MPa, with a maximum difference of 5MPa, and its performance uniformity has been significantly improved.

Finally, it is noted that the above embodiments are only used to illustrate the technical solutions of the present invention without limitation, although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be carried out Modifications or equivalent replacements, without departing from the spirit and scope of the technical solution, should be included in the scope of the claims of the present invention.

Claims (5)

1. A method for improving the performance uniformity of a screw-thread steel poker produced by hot-feeding and direct-rolling is characterized by comprising the following steps:

1) Preparing materials;

2) Smelting in a converter: calculating required alloy according to the component requirements of the ingredients, and smelting in a converter;

3) Continuous casting: pouring the molten steel into qualified square billets, organizing and producing by adopting a hot-conveying direct rolling process, rolling by utilizing the self temperature of continuous casting square billets, preserving heat before cutting the continuous casting square billets, controlling the speed of a heat preservation roller way to be 1.5m/s, and simultaneously supplementing heat to casting blanks by adopting a natural gas and oxygen heat supplementing device in the cutting process;

4) Conveying to a steel rolling mill: after cutting, the billet is quickly conveyed to a steel rolling mill for rolling through a high-speed roller way, wherein the high-speed roller way requires 4.0-5.5 m/min to reduce the temperature drop of the head and the tail of the billet and the temperature difference between the head and the tail of the billet is less than or equal to 25 ℃;

5) Rolling: the initial rolling temperature is 955-985 ℃, and the finish rolling temperature I is: 850-870 ℃, the temperature of finish rolling II is 850-870 ℃, and the temperature of an upper cooling bed is 860-880 ℃;

6) And (4) inspecting, packaging and warehousing: sampling and inspecting the deformed steel bar produced by the hot-conveying and direct-rolling process, and packaging and warehousing.

2. The method for improving the performance uniformity of the deformed steel bar produced by hot-feeding and direct-rolling according to claim 1, which is characterized in that: the deformed steel bar is HRB400E, and comprises the following components in percentage by mass: c:0.22 to 0.25%, si:0.10-0.30%, mn: 1.45-1.60%, P: less than or equal to 0.040%, S: less than or equal to 0.040 percent, and the balance of Fe and inevitable impurities.

3. The method for improving the performance uniformity of the deformed steel bar produced by hot-rolling and straight-rolling according to claim 1, which is characterized in that: the section size of the square billet in the step 3) is 170mm multiplied by 12mm.

4. The method for improving the performance uniformity of the deformed steel bar produced by hot-rolling and straight-rolling according to claim 2, which is characterized in that: in the heat supplementing process in the step 3), pressure regulating valve groups and control systems are arranged on respective main pipes, the gas and oxygen are subjected to split flow control, and the consumption of natural gas is required: 480Nm ³ H, pressure is more than 0.2MPa, and the oxygen consumption requirement is as follows: 960Nm ³ H, the pressure is more than 0.2MPa, the flow of each flow can be adjusted according to the heat supplementing effect, the continuous casting blank is heated to 1000-1030 ℃, and the temperature difference between the head and the tail of the square blank is controlled below 25 ℃.

5. The method for improving the performance uniformity of the deformed steel bar produced by hot-rolling and straight-rolling according to claim 2, which is characterized in that: and 6) respectively detecting the yield strength of the head, the middle and the tail of the deformed steel bar, and packing and warehousing the qualified deformed steel bar if the yield strength fluctuation is less than 15 Mpa.